• Proceedings of the Korean Geotechical Society Conference
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• 2002.10a
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• pp.265-270
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• 2002

Dilatancy is a unique characteristics of granular materials showing the tendency to change volume upon shearing. In this study large triaxial tests were peformed for both the well graded rock and the poorly graded rock. And the shear strength of rockfill materials considering dilatancy is evaluated based on the test results. For the rock materials of this study the contribution of dilatancy in the maximum internal friction angle is as much as -6.0%∼3.0% of the internal friction angle measured at peak

• Journal of the Korea Concrete Institute
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• v.20 no.5
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• pp.583-592
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• 2008

Recently, the effects of high temperature on compressive strength, elastic modulus and strain at peak stress of high strength concrete were experimentally investigated. The present study is aimed to study the effect of elevated temperatures ranging from 20 to 700 on the material mechanical properties of high strength concrete of 40, 60, 80 MPa grade. In this study, the types of test were the stressed test and stressed residual test that the specimens are subjected to a 25% of ultimate compressive strength at room temperature and sustained during heating and when target temperature is reached, the specimens are loaded to failure. And another specimens are loaded to failure after 24 hour cooling time. Tests were conducted at various temperatures ($20{\sim}700^{\circ}C$) for concretes made with W/B ratios 46%, 32% and 25%. Test results showed that the relative values of compressive strength and elastic modulus decreased with increasing compressive strength grade of specimen and the axial strain at peak stress were influenced by the load before heating. Thermal strain of concrete at high temperature was affected by the preload level as well as the compressive strength. Finally, model equation for compressive strength and elastic modulus of heated high strength concrete proposed by result of this study.

• Korean Journal of Poultry Science
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• v.48 no.4
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• pp.319-325
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• 2021

In this study, we investigated the effects of feeding diets with different levels of energy and nutrient density on the egg quality of laying hens during the pre-peak and peak periods. A total of 192 (Hy-line brown) laying hens were used in a 15-week trial. The hens were randomly allotted to one of four treatments, each with four replicates (12 hens per replication). We assessed the effects of four level of dietary energy (2,710, 2,850, 2,870 and 2,890 kcal/kg) and three levels of nutrient density (Methionine + Cysteine: 0.56%, 0.85%, 0.80% and Crude Protein: 14.5%, 19%, 18%). Differences in the energy and nutrient density contents of diets showed no significant effect (P>0.05) on the average daily gain, average daily feed intake, feed conversion ratio, egg weight, or egg production of hens during the pre-peak and peak periods. However, hens subjected to 2,890 kcal/kg during the pre-peak period were found to lay eggs with significantly thicker shells, and yolk color was found to be significant enhanced in hens fed this diet during the pre-and peak periods. In contrast, we detected no significant effects of dietary energy or nutrient density on the Haugh unit or eggshell strength. In summary, increasing the energy level of diets from 2,710 to 2,890 kcal/kg was found to have positive effects on the shell thickness and yolk color of eggs produced by laying hens.

• Proceedings of the KSPS conference
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• 2004.05a
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• pp.161-163
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• 2004

This study concerns the constraints of English Poetic Fixed Meter. In English poems, the metrical pattern doesn't always match the linguistic stress on the lines. These mismatches are found differently among the poets. For the lexical stress mismatched with the weak metrical position, ${\ast}W{\Rightarrow}$ Strength is established by the concept of the strong syllable. The peaked monosyllabic word mismatched with weak metrical position is divided according to which side of the boundary of a phonological domain it is adjacent to. In most poets, ${\ast}$Peak] is ranked higher than ${\ast}$[Peak. In Shakespeare, Adjacency Constraint is ranked higher than ${\ast}$Peak].

• MALSORI
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• no.42
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• pp.71-88
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• 2001

This study is on the constraints of English Poetic Meter. In English poems, the metrical pattern doesn't always match the linguistic stress on the lines. These mismatches are found differently among the poets. The peaks mismatched with the weak metrical position are divided into the two ways according as they are adjacent to the boundary of a phonological domain or not. PAF and $^*UV$] are suggested for the mismatched peak which are not adjacent to the boundary of a phonological domain ; $^*Peak$] and BT for the mismatched peak which are adjacent to the boundary of a phonological domain. For the lexical stress mismatched with the weak metrical position, $^*W{\;}{\Rightarrow}{\;}Strength$ is set up by the concept of the strong syllable. $MPS{\;}{\Rightarrow}{\;}\Phi_{max}$ for the metrical position size can replace the resolution which is used to control the number of syllables in English poems. These constraints show the different hierarchies among the poets.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.4 no.4
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• pp.61-68
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• 1995

TiC-Al2O3 composite ceramics has high hardness, high strength, high wear and corrosion resistance. Therefore, composite ceramics have been concerned significantly with some excellent properties and many functions as new industrial materials to the industry at large. In present research, experiments are carried out to obtain the machinability and machining properties by EDM. As a result, the most suitable machining conditions of TiC-Al2O3 composite ceramics was that the pulse duration is 10-60$mutextrm{s}$, the peak current is 10-16A. The machining speed and the wear of the tool electrode increased with the increase in peak current.

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.1593-1595
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• 2000

We present a new procedure to evaluate the degradation in a lCr-lMo-0.25V steel. The method is based on the existence of the peak of reversible permeability in the differential magnetization around the coercive field strength. The apparatus is based on the detection of the voltage induced in a surface type coil using a lock-in amplifier tuned to a frequency to the exciting one. Results obtained the reversible permeability and Vickers hardness on the annealed samples show the peak interval of reversible permeability and Vickers hardness decreased as ageing time increased. The correlation between Vickers hardness and the peak interval of reversible permeability could well be evaluated non destructively.

• Journal of the Korean Society of Physical Medicine
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• v.14 no.4
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• pp.1-8
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• 2019

PURPOSE: The purpose of this study was to compare the maximum knee strength and endurance of elderly Korean women with Kellgren-Lawrence grade (K-L II) by age. METHODS: In this study, the total number of participants was 50, divided into five groups of 10 by age. Maximum knee muscle strength was measured at a low speed of 60°/sec using Biodex, an isokinetic device for comparison of maximum knee muscle strength, whereas muscle endurance was measured by muscle contraction at a high speed of 180°/sec. The peak torque values of the extensor and flexor muscles in the muscle strength and muscle endurance tests were collected according to each classification. RESULTS: The results of the experiment show that maximum muscle strength and muscle endurance decreased significantly at 60°/sec and 180°/sec during flexion and extension according to age (p<.05). In particular, the age group of 71 to 75 years showed the most significant correlation with other age groups (p<.05). CONCLUSION: The results of this study can be used as basic data for increasing physical activity and muscle strength in women with knee osteoarthritis.

• Structural Engineering and Mechanics
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• v.31 no.6
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• pp.697-716
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• 2009

This paper summarizes an experimental and analytical study on the seismic behavior of high strength reinforced concrete columns under cyclic loading. In total six cantilever columns with different sizes and concrete compressive strengths were tested. Three columns, small size, had a $325{\times}325$ mm cross section and the three other columns, medium size, were $520{\times}520$ mm. Concrete compressive strength was 80, 130 and 180 MPa. All specimens were designed in accordance with the Japanese design guidelines. The tests demonstrated that, for specimens made of 180 MPa concrete compressive strength, spalling of cover concrete was very brittle followed by a significant decrease in strength. Curvature was much important for the small size than for the medium size columns. Concrete compressive strength had no effect on the curvature distribution for a drift varying between -2% and +2%. However, it had an effect on the drift corresponding to the peak moment and on the equivalent viscous damping variation. Simple equations are proposed for 1) evaluating the concrete Young's modulus for high strength concrete and for 2) evaluating the moment-drift envelope curves for the medium size columns knowing that of the small size columns. Experimental moment-drift and axial strain-drift histories were well predicted using a fiber model developed by the authors.

• Earthquakes and Structures
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• v.12 no.4
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• pp.397-407
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• 2017

To estimate the structural seismic demand, some methods are based on an equivalent linear system such as the Capacity Spectrum Method, the N2 method and the Equivalent Linearization method. Another category, widely investigated, is based on displacement correction such as the Displacement Coefficient Method and the Coefficient Method. Its basic concept consists in converting the elastic linear displacement of an equivalent Single Degree of Freedom system (SDOF) into a corresponding inelastic displacement. It relies on adequate modifying or reduction coefficient such as the inelastic deformation ratio which is usually developed for systems with known ductility factors ($C_{\mu}$) and ($C_R$) for known yield-strength reduction factor. The present paper proposes a rational approach which estimates this inelastic deformation ratio for SDOF bilinear systems by rigorous nonlinear analysis. It proposes a new inelastic deformation ratio which unifies and combines both $C_{\mu}$ and $C_R$ effects. It is defined by the ratio between the inelastic and elastic maximum lateral displacement demands. Three options are investigated in order to express the inelastic response spectra in terms of: ductility demand, yield strength reduction factor, and inelastic deformation ratio which depends on the period, the post-to-preyield stiffness ratio, the yield strength and the peak ground acceleration. This new inelastic deformation ratio ($C_{\eta}$) is describes the response spectra and is related to the capacity curve (pushover curve): normalized yield strength coefficient (${\eta}$), post-to-preyield stiffness ratio (${\alpha}$), natural period (T), peak ductility factor (${\mu}$), and the yield strength reduction factor ($R_y$). For illustrative purposes, instantaneous ductility demand and yield strength reduction factor for a SDOF system subject to various recorded motions (El-Centro 1940 (N/S), Boumerdes: Algeria 2003). The method accuracy is investigated and compared to classical formulations, for various hysteretic models and values of the normalized yield strength coefficient (${\eta}$), post-to-preyield stiffness ratio (${\alpha}$), and natural period (T). Though the ductility demand and yield strength reduction factor differ greatly for some given T and ${\eta}$ ranges, they remain take close when ${\eta}>1$, whereas they are equal to 1 for periods $T{\geq}1s$.